U.S. patent application number 11/852567 was filed with the patent office on 2009-03-12 for malware prevention system monitoring kernel events.
Invention is credited to Somesh Jha, Hao Wang.
Application Number | 20090070878 11/852567 |
Document ID | / |
Family ID | 40433303 |
Filed Date | 2009-03-12 |
United States Patent
Application |
20090070878 |
Kind Code |
A1 |
Wang; Hao ; et al. |
March 12, 2009 |
MALWARE PREVENTION SYSTEM MONITORING KERNEL EVENTS
Abstract
A malware prevention system monitors kernel level events of the
operating system and applies user programmable or preprepared
policies to those events to detect and block malware.
Inventors: |
Wang; Hao; (Madison, WI)
; Jha; Somesh; (Madison, WI) |
Correspondence
Address: |
BOYLE FREDRICKSON S.C.
840 North Plankinton Avenue
MILWAUKEE
WI
53203
US
|
Family ID: |
40433303 |
Appl. No.: |
11/852567 |
Filed: |
September 10, 2007 |
Current U.S.
Class: |
726/24 |
Current CPC
Class: |
G06F 21/554 20130101;
G06F 21/52 20130101 |
Class at
Publication: |
726/24 |
International
Class: |
G06F 12/14 20060101
G06F012/14 |
Goverment Interests
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0001] This invention was made with United States government
support awarded by the following agencies:
[0002] DOE W-7405-ENG-36
[0003] NSF 0524051
[0004] The United States has certain rights to this invention.
Claims
1. A computer program stored in a computer readable medium and
executable on a computer using an operating system to run benign
processes, the computer program executing to: (a) monitor kernel
events of the operating system associated with processes executing
on the computer; (b) evaluate the monitored kernel events against
stored policies describing sequences of kernel events associated
with malware; and (c) block execution of at least one process
associated with kernel events identified by a stored policy as
indicating malware.
2. The computer program of claim 1 wherein the monitoring of step
(a) is performed before the kernel event is committed to a system
resource and wherein the blocking of the execution of the at least
one process terminates a kernel event associated with the at least
one process.
3. The computer program of claim 1 wherein the computer program is
implemented within the operating system.
4. The computer program of claim 1 wherein the computer program is
implemented as a driver in the Windows operating system.
5. The computer program of claim 1 wherein the computer program is
implemented as a dynamically linked library in the Windows
operating system.
6. The computer program of claim 1 wherein the evaluation of step
(b) includes the step of mapping low level-kernel events to
higher-level events described by the stored policies.
7. The computer program of claim 1 wherein the stored policies
accept as arguments the monitored kernel events and stored states
derived from previous kernel events.
8. The computer program of claim 1 wherein the kernel events may
identify functions selected from the group consisting of: creation
of a process, termination of a process, opening of a file, closing
of a file, opening of a network socket, closing of the network
socket.
9. The computer program of claim 1 wherein at least one stored
policy identifies as malware a file created by a given process and
then subsequently executed by the given process.
10. The computer program of claim 1 wherein the policies may be
limited in application to identified predicate processes.
11. The computer program of claim 10 wherein the policies are
applicable to child processes of the identified predicate
processes.
12. The computer program of claim 1 wherein the policies are
authored in a policy language linking kernel events with actions
where the actions include stopping a kernel event or allowing the
kernel event to proceed.
13. The computer program of claim 12 wherein the actions further
include storing the kernel event in a state database and the policy
language links kernel events in the state database with
actions.
14. The computer program of claim 12 wherein the actions further
include logging the kernel event with a time stamp.
15. The computer program of claim 1 wherein the stored policies are
held in a file updatable by a user.
16. A computer system comprising: at least one processor
communicating with resources including computer memory; an
operating system program stored in the memory and executing on the
processor; one or more application programs stored in memory and
executing on the processor under control of the operating system;
wherein the operating system operates to: (a) monitor kernel events
associated with processes executing on the computer; (b) evaluate
the monitored kernel events against stored policies describing
sequences of kernel events associated with malware; and (c) block
execution of a process associated with kernel events identified by
a stored policy as associated with malware.
17. A computer program stored in a computer readable medium and
executable on a computer to: (a) monitor kernel events of an
operating system associated with processes executing on the
computer; (b) evaluate the monitored kernel events against stored
policies composed in a human readable policy language describing
sequences of kernel events associated with malware and actions in
response to the sequences of kernel events; and (c) execute an
action of the policy language to block execution of at least one
process associated with kernel events identified by a stored policy
as indicating malware.
18. A method of detecting malware on an electronic computer having
an operating system with an operating system kernel managing the
execution of multiple processes including benign processes and
inadvertent malware processes, the method comprising the steps of:
(a) monitoring operating system kernel events associated with
processes executing on the computer; (b) evaluate the monitored
kernel events against stored policies describing sequences of
events associated with malware; and (c) block execution of a
process associated with kernel events identified by a stored policy
as associated with malware.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
BACKGROUND OF THE INVENTION
[0005] The present invention relates to computer programs for
detecting malicious programs such as spyware and the like.
[0006] Malicious programs or "malware" have become a significant
problem in the computer industry. Examples of such malware include:
"viruses" which are programs attached to documents or other
programs and that activate themselves within a host computer to
self-replicate for further spreading; "worms" which are programs
that self-replicate to transmit themselves across a network;
"Trojans" or "Trojan horses" which are programs that masquerade as
useful programs but contain portions to attack the host computer or
leak data; "back doors" which are programs that open a system to
external entities by subverting local security measures; and
"spyware" which are programs that transmit private-user data to an
external entity. More generally malware is malicious software
intentionally included or inserted in a system for a harmful
purpose.
[0007] Spyware, in particular, has become a significant security
threat. Some studies have suggested that as many as 69% of the
computers connected to the Internet have been infected with spyware
at some point in time. The damages caused by spyware (e.g. stolen
credit card numbers) are not limited to disruption of the infected
computer system, yet unlike some other types of malware, spyware
may not noticeably degrade the performance of the computer.
[0008] Methods for detecting malicious programs may be classified
as dynamic or static. In dynamic methods, the suspected program is
executed in a "sandbox". A sandbox is a safe execution area created
in a computer that uses hardware and/or software to prevent the
executing program from damaging interaction with the computer.
During execution of the malware in the sandbox, attempts by the
malware to interact with the computer, such as by writing data
outside of a predefined memory area, are monitored. The constraints
placed on the sandbox make it an impractical environment for the
execution of normal programs, and this technique is normally used
off-line for research purposes.
[0009] Static detection does not require execution of the suspected
program, but instead reads and analyzes the program instructions or
"code" before it is executed. One "heuristic" detection technique
looks for changes in certain program locations (normally the
beginning and end of the code) where the virus is likely to be
attached. A second "signature" detection technique checks for known
virus-specific sequences of instructions (virus signatures) inside
the program. Such signature detection is effective when the virus
does not change significantly over time and when multiple viruses
have the same signature.
[0010] Most malware detection and prevention systems intended for
real-time defense of an operating computer use a signature
detection system performing a background scanning of files to
detect signatures of known malware. This signature-based solution
has two major shortcomings. First it is ineffective against novel
malware for which no signature has been developed. Second, it is
ineffective against known malware that has been modified with minor
changes ("obfuscation)" which can defeat the signature scanning
technique.
BRIEF SUMMARY OF THE INVENTION
[0011] The present inventors have recognized that much malware and
specifically spyware can be detected by monitoring kernel events
generated by the operating system in response to the malware's
execution. These events, which are essential to the function of the
malware, are not easily disguised. Different sequences of events
associated with different malware can be captured in a set of
policies written in a general policy language. The policies may
block selected kernel events to prevent execution of the malware
after it has been detected. By monitoring and controlling kernel
events within the operating system, the invention is protected
against being disabled by the malware and may operate in real time
with very low overhead.
[0012] Specifically, the present invention provides a computer
program executable on a computer running an operating system and
executing benign and possible, unrecognized malware processes. The
computer program works with or as part of the operating system to
monitor kernel events of the operating system associated with all
processes executing on the computer. The monitored kernel events
are evaluated against stored policies describing sequences of
kernel events associated with malware, and the program stops
execution of at least some processes that are associated with
kernel events identified by a stored policy as being malware.
[0013] It is thus a feature of one embodiment of the invention to
identify malware based not on the malware code itself but on the
kernel level events generated by the malware. By monitoring low
level events, early and reliable detection of the malware is
possible. Further the technique may be simply integrated into a
running computer with little loss in the performance of the
computer
[0014] The monitoring step may be performed before the kernel event
is committed to a system resource and the stopping of the process
may be done by blocking at least one of the kernel events
associated with the process.
[0015] It is thus a feature of one embodiment of the invention to
provide a simple mechanism for terminating malware behavior. By
trapping the event, the malicious behavior is averted with minimal
disruption to other programs including, for instance, a partially
benign program having some spyware features that the user may wish
to disable.
[0016] The computer program may be implemented within the operating
system kernel.
[0017] It is thus another feature of one embodiment of the
invention to provide a malware solution that is both better
resistant to disabling by malware (as it resides in the kernel) and
that may be executed in real time using an actual fully functional
operating system.
[0018] The computer program may be implemented as a driver in the
Windows operating system.
[0019] It is thus another feature of one embodiment of the
invention to provide a solution that is applicable to the widely
used Windows operating system where access to the code of the
underlying kernel is not available to the public.
[0020] The computer program may be implemented as a dynamically
linked library in the Windows operating system.
[0021] It is thus another feature of one embodiment of the
invention to provide a program that may be quickly implemented on a
Windows-type computer without modification or recompiling of the
Windows kernel.
[0022] The evaluation step may include the step of mapping low
level kernel events to higher-level events, the latter described by
the stored policies.
[0023] It is thus another feature of one embodiment of the
invention to derive high-level (and universal) operating system
functions from kernel level events that may individually be
ambiguous as to function or unique to a particular operating
system.
[0024] The stored policies may accept as arguments the monitored
kernel events as well as stored states derived from previous kernel
events.
[0025] It is thus another feature of one embodiment of the
invention to provide a policy structure that is sensitive to
historical state and thus which may detect malware operating over a
long time period.
[0026] The kernel events may identify functions selected from the
group consisting of: creation of a process, termination of a
process, opening of a file, closing of a file, opening of a network
socket, and closing of a network socket.
[0027] It is thus a feature of one embodiment of the invention to
provide a malware detection system that may flexibly combine core
kernel level functions.
[0028] The stored policy may identify as malware a file created by
a given process and then subsequently executed by the same given
process.
[0029] It is thus a feature of one embodiment of the invention to
provide a system that may detect the common malware exploit of a
"drive-by download".
[0030] The policies may be limited in application to identified
predicate processes.
[0031] It is thus a feature of one embodiment of the invention to
be able to tailor the detection process to the particular
application being run.
[0032] The policies may be applicable to child processes of the
identified predicate processes.
[0033] It is thus a feature of one embodiment of the invention to
allow the policies to track processes created by a given predicate
process.
[0034] The policies may be authored in a policy language linking
kernel events with actions where the actions include stopping a
kernel event or allowing the kernel event to proceed. In addition,
the actions may further include storing the kernel event in a state
database and the policy language may link kernel events in the
state database with other kernel level events. One action may be
logging the kernel event with a time stamp.
[0035] It is thus a feature of one embodiment of the invention to
provide a flexible policy language that may capture a variety of
malware identifying functions.
[0036] These particular features and advantages may apply to only
some embodiments falling within the claims and thus do not define
the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] FIG. 1 is a simplified block diagram of a desktop computer
suitable for use with the present invention to execute an operating
system and associated application programs;
[0038] FIG. 2 is a block diagram of the operating system of FIG. 1
showing integration of the present invention with that operating
system as a driver;
[0039] FIG. 3 is a block diagram of the program of the present
invention receiving kernel level events from the operating system
and mapping the kernel level events to higher-level events applied
to policies stored in a policy engine;
[0040] FIG. 4 is a schematic representation of the mapping process
of FIG. 3 converting low-level kernel level events into higher
level events described by policies of the policy engine;
[0041] FIG. 5 is a simplified representation of a state table used
in the present invention for preserving states utilized by the
policies; and
[0042] FIG. 6 is a simplified representation of the storage of the
policies in the policy engine for rapid access.
DETAILED DESCRIPTION OF THE INVENTION
[0043] Referring now to FIG. 1, a typical computer system 10
suitable for use with the present invention may provide a processor
12 communicating with a memory 14 and with interfaces 16 and 18 via
an internal bus 20.
[0044] Interface 16 may provide for connections to a display
monitor 24 and one or more input devices including keyboard 26 and
cursor control device 28 such as a mouse. Interface 18, for
example, may be a standard Ethernet interface communicating with
the Internet 22. Such a computer system 10 represents a typical
personal computer of a type well known in the art.
[0045] Referring now to FIGS. 1 and 2, the memory 14 of the
computer system 10 may hold an operating system kernel 30, for
example, the Windows operating system manufactured by Microsoft of
Redmond Calif. As is generally understood in the art, the kernel 30
is a computer program that provides an interface between the
hardware 34 of the computer system 10 and one or more application
programs 32, for example, a word processor or a browser program,
running on the computer system 10.
[0046] The kernel 30 includes an executive portion 36, which in the
Windows operating system manages basic I/O, memory and the
execution of a variety of processes (actual execution of a
program's instructions) on the computer system 10. The executive
portion 36 communicates with the hardware through a set of drivers
38 and 40 which form part of a "hardware abstraction layer" 39
allowing one version of the kernel 30 (and hence one version of the
application programs 32) to work interchangeably with a variety of
hardware configurations.
[0047] Drivers 38 and 40 are programs often written by
third-parties that may be integrated into the kernel 30. Commonly
this integration is done at run time through the use of linked
libraries holding the drivers, termed "dynamically linked
libraries" or DLL's in the Windows operating system. The lower
level drivers 38 provide for a common software interface to unique
hardware elements (for example a video card). Windows also allows
for higher level non-device drivers termed "filter drivers" 40
positioned above the lower level drivers 38.
[0048] The executive portion 36 communicates with the drivers 40
and 38 through a set of operating system messages termed: "kernel
events" 42 that pass instructions and data among various components
of the kernel 30. The filter drivers 40 are positioned to receive
kernel events 42 before the lower level drivers 38 and may modify
or terminate a kernel event 42 before it is received by other
drivers 38. The filter drivers 40 provide the present invention
with access to kernel event 42.
[0049] Referring now to FIG. 3, the present invention employs a
filter driver 40' (that is a program written to conform with the
requirements of a filter driver for the operating system) receiving
kernel events 42 and optionally passing those kernel events 42' to
other drivers 38. The filter driver 40' may be a DLL and thus
dynamically linked to the operating system to operate logically
within the kernel 30 as shown in FIG. 2.
[0050] The filter driver 40' may incorporate or communicate with a
kernel event mapper 44 which takes kernel events 42 and maps them
to high-level events 46. These high-level events 46 are then
provided to a policy engine 48 which holds a set of policies 50, as
will be described below, which analyze the high-level events 46 to
determine whether they reflect possible activity of malware. The
policy engine 48 includes a state table 52 that will be used to
allow the policies 50 to react to historical high-level events 46.
Depending on the particular instructions of the policies 50, the
policy engine 48 may load the high-level events 46 or kernel events
42 in a log file 54 providing a chronological, time-stamped event
log of the events as they are received.
[0051] Referring now to FIG. 3, the kernel event mapper 44 may
receive different kernel events 42a-42d and map them to a single
high-level event 46a. Alternatively a single kernel event 42e
(depending on its arguments) may map to different high-level events
46b and 46c.
[0052] For example, a high-level event 46a may be "Delete a file"
expressed as follows:
[0053] DeleteFile (filename, pid)
[0054] indicating that a file having "filename" is to be deleted as
requested by a process having a process identification number
"pid", a unique number assigned to the process creating the file by
the operating system. Here the high-level event 46a is mapped from
any of multiple kernel events 42a-d of:
[0055] IRP_MJ_SET_INFORMATION (filename, pid, IRP, Device)
[0056] or
[0057] IRP_MJ_CLEANUP (filename, pid, IRP, Device)
[0058] or
[0059] IRP_MJ_CREATE (option, filename, pid, IRP, Device)
[0060] If the low-level kernel event 42 is IRP_MJ_SET_INFORMATION
and the "IRP" parameter is "FileDispositionInformation" and the
file is marked for deletion, then this low-level event is a
DeleteFile; otherwise it is not. Similarly, if the low-level kernel
event 42 is IRP_MJ_CLEANUP and the "IRP" parameter is
"DeletePending" or "DeleteOnClose", then this is also a high-level
DeleteFile event.
[0061] An example high-level event 46c mapped from a single kernel
level event 42e may be "Creating a new file". Such an event might
be expressed as follows:
[0062] CreateFile (filename, filehandle, pid)
[0063] where "CreateFile" is the name of the high-level event 46,
and "filename", "filehandle", and "pid" are parameters (arguments)
of the high-level event 46c in which "filename" is the name of the
file that is to be created, "filehandle" is a unique identifier
created by the operating system (OS) to track open files, and "pid"
is the process identification number. "filehandle" is obtained
through the "IRP" parameter of the call IRP_MJ_CREATE. This
high-level event 46c (CreateFile(filename, filehandle, pid)) may be
mapped from a single kernel event 42e:
[0064] IRP_MJ_CREATE (option, filename, pid, IRP, Device)
[0065] where the parameters of CreateFile are simply the
corresponding parameters of the kernel level event IRP_MJ_CREATE
and this mapping occurs when the "option" parameter is "Overwrite",
or "Create". If the "option" parameter is "Open", or "Open If",
then this low-level kernel event 42e maps to a different high-level
event 46b of OpenFile.
[0066] By remapping the kernel events 42 as high-level events 46
the complexity of the policy 50 is greatly reduced and the policies
50 be made platform independent.
[0067] Each policy 50 is written from policy instructions linking
events, predicates, actions, and states. The policy language may
best be understood by reference to an example policy for detecting
a drive-by download, that is, a situation where an element of
malware installed on the computer downloads additional malicious
programs from the Internet and then executes those programs. A
policy 50 blocking a drive-by-download could be written per Example
1 as follows:
EXAMPLE 1
TABLE-US-00001 [0068] 1 Policy NoDriveByDownload : [iexplore.exe,
firefox.exe] 2 Event CreateFile(filename, handle, pid) 3
FileState.Map(filename, pid); 4 Return ALLOW; 5 EndEvent; 6 Event
CreateProcess(filename, pid, parentPid) 7 if
(FileState.GetOwner(filename) == parentPid) then 8 LOG 9 Return
DENY; 10 end 11 EndEvent;
[0069] Line 1 of this policy provides an instruction that marks the
beginning of the policy 50 and designates its name
"NoDriveByDownload" followed by predicate processes, in this case
Internet Explorer or Firefox, two well-known Internet browsers, to
which this policy will apply. If no predicate processes are
designated, the policy will apply to all processes.
[0070] Line 2 is an event instruction that responds to the
high-level event 46 "CreateFile", the operating system event that
will create a file, for example, on a disk drive. This high-level
event 46 carries with it parameters: "filename", "filehandle", and
"pid" that may be used by the rest of the process. At line 3, this
high-level event 46 is stored in the state table 52 for reference
by this or future policies. The instruction at line 4 then provides
an action which allows the underlying kernel events 42 to be passed
to other drivers 38 of the operating system as indicated by kernel
event 42' of FIG. 3. Line 5 marks the end of that event instruction
begun at line 2.
[0071] This policy 50 also includes a second event instruction at
line 6 triggered by a CreateProcess high-level event 46, that is,
an event that starts a new process executing under the operating
system. At line 7, the state table 52 is interrogated to identify
the process that created (loaded) the executable file that will now
be started in the CreateProcess event. In a drive-by downloading
attack, the process associated with this filename will have been
previously stored in the state table 52 at line 3 of the
NoDriveByDownload policy.
[0072] If the process trying to execute the file (in the
CreateProcess event) is the same process that created the process
to be executed (in the CreateFile event) then, at line 7, an
interrogation of the state table 52 and test will indicate a
drive-by-download and the policy will log this information in the
log file 54 (typically logging high-level event 46 and a timestamp
but possibly logging kernel events 42) denying the kernel event 42
underlying the CreateProcess high-level event 46. This Deny action
may simply block the kernel event 42 from other drivers 38
effectively preventing the process creation. Lines 10 and 11 end
the second event instruction and the policy respectively.
[0073] Referring to FIG. 5, generally the logging process (of line
8 above) builds a log file 54 providing a set of logical rows
associated with a timestamp (the fourth column) and recording the
logged high-level event 46 (in the first column), its parent
process (in the second column) and any parameter data (in the third
column). This log file 54 may be used for forensic analysis of the
operation of the malware and to generate new policies.
[0074] The following Table 1 shows the wide variety of different
high-level events 46 that may form the basis of the instructions of
policies 50. As can be seen, the event types cover core operating
system activities such as managing files, opening and closing
network sockets, starting and stopping processes that are being
executed, and managing the system registry.
TABLE-US-00002 TABLE 1 Event Type Event Name Arguments Description
File OpenFile {filename, handle, Open a file pid} CloseFile
{handle, pid} Close a file CreateFile {filename, handle, Create a
file pid} DeleteFile {filename, pid} Delete a file RenameFile
{oldfile, newfile, Rename a file handle, pid} ReadFile {handle,
pid} Read from a file WriteFile {handle, pid} Write to a file
Network OpenSocket {socket, pid} Open a network socket CloseSocket
{socket, Close a network socket Connect {socket, address, Connect
to an pid} address Disconnect {socket, pid} Disconnect Send
{socket, data, pid} Send data Receive {socket, data, pid} Receive
data Listen {socket, pid} Listening on a handle Process
CreateProcess {filename, pid, Create a process parentPid}
TerminateProcess {pid} Terminate a process LoadImage {pid,
imagePath} Load code (e.g., a DLL) Registry OpenRegKey {key, pid}
Open a registry key CloseRegKey {key, pid} Close a registry key
CreateRegKey {key, pid} Create a registry key DeleteRegKey {key,
pid} Delete a registry key CreateRegValue {key, value, data, Create
a key value pid} DeleteRegValue {key, value, pid} Delete a key
value SetRegValue {key, value, data, Change a value pid}
[0075] The following Table 2 shows the different types of actions
that may be implemented by policy 50 in response to events and
states:
TABLE-US-00003 TABLE 2 Action Type Actions Description Enforcement
ALLOW Allow an event to proceed DENY Stop an event Logging LOG Log
the event Policy State (Update) FileState.Map(pathname, pid) Map a
file to the process that created it FileState.Unmap(pathname) Unmap
a file from the FileState NetworkState.Map(socket, address) Map a
socket to an address NetworkState.Unmap(socket) Remove a socket
from the mapping ProcessState.Map(pid, pathname) Map a process id
to its binary image ProcessState.Unmap(pid) Unmap a process
ProcessState.AddWhiteList(pid) Add a process to the white list
ProcessState.RemoveWhiteList(pid) Remove a process from the white
list ProcessState.AddBlackList(pid) Add a process to the black list
ProcessState.RemoveBlackList(pid) Remove a process from the black
list Policy State(Query) FileState.GetOwner(pathname) Return the
owner process PID for a file NetworkState.GetAddress(socket) Return
the remote address associated with the socket
ProcessState.InWhiteList(pid) Check to see if a process is in the
white list ProcessState.InBlackList(pid) Check to see if a process
is in the black list ProcessState.IsFamily(pid1, pid2) Check to see
if two processes belong to the same process tree
[0076] As can be seen, generally the policy instructions support
three types of actions: enforcement, logging and state maintenance.
Enforcement actions DENY or ALLOW a particular event. The DENY
action directly affects the proper execution of a monitored
process. For a CreateProcess event, a DENY action will terminate
the process. For other events, denying means the request associated
with the event is not committed to the resource.
[0077] Logging actions indicate whether to log (LOG) the
intercepted event in the log file 54.
[0078] State actions store information in the state table 52 and
can be divided into two groups: Update and Query. Update actions
update the state table 52 while Query actions retrieve information
from the state table 52.
[0079] The flexibility of the policy system which allows the user
to write policies 50 or to use prewritten policies to address a
variety of malware situations may be illustrated in the additional
following examples.
[0080] Example 2 shows a policy to block Trojan horses (Trojans).
In this case, because it is not known what process might spawn
Trojan behavior, no predicate processes are provided. This policy
is generally very similar to the NoDriveByDownload policy described
above, with the exception of lines 3 and 4 which check to see if a
process is attempting to create a file in the Windows system
directory and the process is not contained in a "white list" of
processes that should be creating files in the Windows system
directory. At lines 11-13 an attempt to set a registry value
triggers a check to see if the data to be set is owned by the same
process or a process in the same family as the process as doing the
setting and if the registry key is in a list of sensitive registry
keys. If so, the setting of the registry is denied.
EXAMPLE 2
TABLE-US-00004 [0081] 1 Policy NoTrojans 2 Event
CreateFile(filename, filehandle, pid) 3 if RegMatch(filename,
"C:\Windows\*") AND !Process.InWhiteList(pid) then 4 Return DENY; 5
else 6 FileState.Map(filename, pid); 7 Return ALLOW; 8 end 9
EndEvent 10 Event SetRegValue(key, value, data, pid) 11 owner =
FileState.GetOwner(data); 12 if (ProcessState.IsFamily(owner, pid)
AND 13 Match(key, SensitiveRegKey))" then 14 LOG; 15 Return DENY;
16 end 17 EndEvent
[0082] Example 3 shows a different policy that disables an
objectionable spyware feature of a program, for example, a music
playing program (MusicPlayer), that is otherwise desirable for the
purpose of playing music. In lines 2-5, any process that opens a
particular type of file (in this case an MP3 file) is placed on a
blacklist based on the suspicion that MusicPlayer is logging
information about a user's private music choices. At lines 8-11,
the blacklist created at lines 3-5 is employed to prevent data from
being sent by MusicPlayer to a remote location. It should be noted
that blocking the registry modification does not block the
beneficial playing of the music file by the MusicPlayer
program.
EXAMPLE 3
TABLE-US-00005 [0083] 1 Policy MusicPlayer: [musicplay.exe] 2 Event
Openfile(filename, filehandle, pid) 3 if RegMatch(filename,
"*.mp3") then 4 ProcessState.AddBlackList(pid); 5 Return ALLOW; 6
end 7 EndEvent; 8 Event Send(socket, pid) 9 if ProcessState.
InBlackList(pid) then 10 Return DENY; 11 end 12 EndEvent
[0084] Referring now to FIG. 6, event instructions of each policy
50 may be sorted according to the high-level events 46 they are
triggered by, the latter which may serve as an index to affected
policies 50. In this way, as high-level events 46 are detected,
they may rapidly be matched to the relevant policies 50 in real
time with very little resource consumption in terms of processor
bandwidth.
[0085] While the present invention has been described with respect
to the Windows operating system, it will be understood that these
techniques may be even more easily apply to open source operating
systems such as Linux that permit programs to be written to monitor
and modify kernel level events or that allow the operating system
to be modified to implement the procedures of the present
invention.
[0086] The present invention contemplates that it will be used on a
standard operating system running on an individual standalone
computer. Nevertheless it will be understood that the invention may
also be applicable to operating systems operating in a
virtualization environment either as implemented in the operating
system or the virtualization operating system.
[0087] The present invention has been described in terms of the
preferred embodiment, and it is recognized that equivalents,
alternatives, and modifications, aside from those expressly stated,
are possible and within the scope of the appending claims.
* * * * *